Telephone-exchange system.



A. E. LUNDELL.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAY 25. 1915 1,242,008. Patented Oct. 2,1917.

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A. E. LUNDELL. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAY 25, 19I6.

Patented Oct. 2, 1917.

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ALBEN E. LUNDELL, or New Years,- n. it, Assmnon TO w STERN ELECTRIC COMPANY,

INCORPORATED, 013 NEW YORK, N. Y.. A'CORPOBATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

- Application'filed May 25, 1916. Serial No. 99,748.

To all whom it may concern: j r i Be it known that I, ALBEN E. LUNDELL, a citizen of the United States, residing at New York, in the county of- Bronx and State of New York, have invented certain new and useful Improvements in Telephon'e- Exchange Systems, of which the following is a full, clear, concise, andexact description.

This invention relates to-telephone-exchange systems and moreparticularly to'the supervision of connections in telephone exchanges.

In telephone systems in which connections are established through a plurality-of offices, it was found desirable, for. the purpose of saving current, to provide so-called dry trunks between oflices, 56., trunks through which no supervisory currentitlows during Current flows through the dry trunks only.thuing. the setting up and the severing of the connection. Thesupervisory means, 6. g.,a relay provided in the incoming circuit, is responsive to this current and in turn controls a supervisory-Sig n'al ata connecting operators position.

In order to prevent the untimely vactuation of the supervisory means in systems of this type, it is the object *of thepresent invention to delay the actuation of the supervisory means during the establishmentof the connection for a sufiicient' time to permit an attendant to complete the establishment of a -call, whereupon the current sourcewill be disconnected from the tnunkuntil the severing of the 1 connection.

Inthe drawings, Figures and2, Qplaced side by'side, represent :the circuit arrangement of a-semieautomatic telephone exchange system, only so much being shown of the circuits and apparatus asis necessary for a clear understanding of the present invention. 1

A connecting operator, whose position is indicated in Fig. 1, extends an incoming line to a B operator s position located at a second oifice (shown in Fig.- 2 to the leftrof the dotted line) by operating selector switches 10 and 11 under thecontrol of her sender. The sender and'the selector switches are only schematically shown in the-drawings. Preferably, the sender, the selector switches and the associated controlling apparatus .de-x

scribed in my Patent No. 1,168,319 of Jannary 18, 1916,- are usedin this system By means of her sendemthe'connecting operator Specification of Letters Patent.

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actuates also an indicating device 100 at the B operators position for informing this operator of the numberof the desired subscriber. The indicators 101 1.02 103 and 104 are-of the well-l nown sequence switch type: described'in the. above mentioned patent, and may control, in their actuated positions, any well-known visual or audible signals.' The B operator confers through a call circuit 105 with a- G operator located at a third exchange (shown in Fig.2 to the right of the dotted line), and this operator estab-v li shes the connection with the called line. The trunk extending from a jack 136 at the B operator s position to a repeating coil 1A4 at the .C eperators position is a dry trunk. Aclear understanding'of the invention may be had from the following detailed de scription and the appended claims.

' -.A calling subscriber at substation- 12 defrom the switchhook, causing thereby the display of a well-known cal-ling signal13 in front of the connecting operator, who in serts a plug ltinto an answering jack 15 of the substation 12, establishing a circuit from ground through the winding-of a relay 16, the sleeve contacts of plug .14 and jack 15, and the winding of a cut-'ofi' relay 17, to grounded battery. Relay 17 causes the ex,- tinguishing of signalzl3, and relay 16 closes acircuit from ground, through its armature and front contact, a contact 18," and the power magnet-iof a sequenceswitch 19 to grounded battery. Under the'control of a normal spring 20, this sequenceswitch is moved into position 11.

The cgmnecting operator converses in the well-known manner with the calling subscriber. and then sets up on her keyboard (not shown) the number of a second officeand also the number 0f the called subscriber. In positions 2 and 1 of a sequence-switch associated with the sender, the selectors 10 and 11 are under control of said sender. After selector 11 has seized the desired trunk conductors 21 and 22, leading to the B operators position located at the second office, the-sender sequence switchwillv be in position 8.. A circuit is-thus established from ground, through a. contact 111 ofa sequence switch 112, conductor 22, the lower brushes of selectors 11 and 10, a contact 28 of sequence switch 19, a contact-24 the sender sequence switch, the armature and back con tact of the Zero counting relay 25 associated with the sender, the winding of a sender stepping relay 26, contact 27 of sequence switch 19, the upper brushes of se lectors l0 and 11, trunk conductor 21, con tact 113 of sequence switch 112, and the winding of a stepping magnet 114 associated with the indicating device 100, to grounded battery. This magnet 114 is adapted to move arm115 of the indicating device upon its de'e'nergization. The magnet 114 establishes, upon its ener 'ization, a circuit from ground, through its armature and front contact, arm 115, and the power magnet of the indicator 101 to grounded battery. Indicator 101 is thus set in motion and closes upon each step, a contact 120, thus causing the connection of a ground to the above traced fundamental circuit for short-circuiting the stepping magnet 26 of the sender a desired number of times. A more complete disclosure of the indicator arrangement may be had from my application Serial No. 121,565, filed September 22, 1916. As well known, under the control of the stepping relay 26, the counting relays are successively operated, and when the last or zero counting relay 25 becomes actuated, it opens the fundamental circuit at its back contact, causes the deenergization of step ping magnet 114 of the indicating device and the stepping of the sender sequence switch into position 10. Upon the deenergization of magnet 114, arm 115 connects in circuit indicator 102, and the operation of this indicator and the other indicators is controlled in the same manner as described in connection with indicator 101, for causing the display of the called subscribers designation, at the B operators position. Indicators 101, 102 and 103 control at their contacts 121, 122 and 123, respectively, the operation of stepping magnet 26.

Upon the displacement of indicator 104 from its normal position, a contact 124 is closed, and wien the stepping magnet 114 becomes deenergized upon the moving of the sender sequence switch out of its 14th position, a circuit is established from ground, through the armature and back contact of magnet 114, contact 124, a contact 125 and the power magnet of sequence switch 112 to grounded battery, for moving this sequenceswitch under the control of its normal spring 125 out of position 1 and into position 4.

The sender sequence switch is moved from position 14 to 16, and thus, after the setting of the indicating device 100, a circuit is established from ground through sendersequence switch contact 30, a contact 31 and the power magnet of sequence switch 19 to grounded battery, for moving sequence switch 19 into position 14. In this posi tion of sequence switch 19, a lamp 32 is lighted, indicating to the connecting operator that the B operator has been reached and informed of the ninnber of the called subscriber. There is another lamp 33 pro vided at the position of the connecting operator which indicates that disconnection is desired. This lamp may be lighted in posi tion 16 of sequence switch 19, when a supervisory relay 34 is deenergized, In order to prevent the giving of a false disconnecting signal to the connecting operator, the moving of sequence switch 19 into position 16 must be delayed until this supervisory relay 34 is energized and means must be pro vided for permitting the C operator to cont plete the connection to the called subscrib ers station. This is accomplished in the following manner.

When sequence switch 112 reached position 4, a. circuit was closed from grounded battery, through the winding of a relay 130, contact 131 of sequence switch 112, trunk conductor 21, the upper brushes of selectors 11 and 10, contact 35 of sequence switch 19, and a secondary winding of a repeating coil 36, to ground. Relay 130 closes a circuit from ground, through its armature and front contact, contact 132, and the power magnet of sequence switch 112 to grounded battery, for moving this sequence switch into position 7. The B operator depresses now a call circuit button 133, thus connecting her head set 134 through the call circuit 105 to a head set 135 of the C operator. The B operator informs the C operator of the number of the desired subscriber, and receives also instructions from the C operator as to which trunk to use.

Supposing that the instruction was to use the trunk terminating in a jack'136 in front of the B operator, this operator inserts plug 137 into this jack, establishing thus a circuit from grounded battery, through the winding of a relay 138, the sleeve contacts of plug 137 and jack 136, and a resistance 139 to ground. Relay 138 closes a circuit from ground, through its armature and front contact, acontact 140 and the power magnet of sequence switch 112 to grounded battery, for moving this sequence switch into position 9.

A further circuit is established from the positive pole of battery, through the lower winding of a relay 141, a contact 142 of a relay 143, a primary winding of a repeating coil 144, the ring contacts of jack 136 and plug 137, the winding of a relay 145, the tip contacts of plug 137 and ack 136, a primary winding of repeating coil 144, a contact 146 of relay 143 and the upper winding of relay 141 to the negative pole of battery. Relay 141 closes a circuit from ground, through its armature and front contact, the Winding of a relay 150, the lower back contact and armature of a relay 151, and a lamp 152 to grounded battery. Relay 150 becomes: en-

but establishes, through its contact 153 and a resistance 154, a local energizing circuit forrelay 141. -Relay'145 being deenergized,

. the moving of sequence switch 112Iinto position 17 must be delayed in order to give the G operator sufficient time to insert a plug 154 into a jack-155 in which the calledsub scribers line terminates. z

Gommutator segments 157 and- 158 are mounted on a constantly rotating shaft 1.56 in such a manner thatthe conducting segment of plate 157 contacts with its-brush about two seconds ahead of the conducting segment of plate 158. Plate-15 7 closes, through contact 160-, a driving circuit for sequence switch 112 and moves: it into position 10. During the time interval elapsing between the closure of the driving circuits at the com mutator segments 157 and 158,-the C operator inserts plug 154 into jack'155, closing :a circuit from grounded battery through a cut-off relay 165, the sleeve contacts of jack 155 and plug 154 and the winding of relay 151 to ground. Relay 151, upon energization, opens the circuit including -lam'p l52 and relay 150. Relay=150iopens the energizing circuit of relay 143, and this relay reestablishes thecircuitfor the relay 145. The

- C operator operates her ringing key 166, for

signaling the called subscriber and this subscriber, by removing the receiver, operates in the well-known manner, a supervisory relay 167. Relay 167 establishes a circuit through its armature and front contact for relay 143, and this relay again opens the circuit of relay 145.

After the time interval of two seconds has elapsed, plate 158 closes a driving circuit through sequence switch contact 161, for moving sequence switch 112 into position 17. A circuit is now closed from ground, through the armature and back contact of relay 145, a sequence switch contact 162, a retardation coil 163, a sequence switch contact 164, trunk conductor 22, the lower brushes of selectors 11 and 10, a sequence switch contact 40, the winding of a supervisory relay 34, and the secondary winding of repeating coil 36, to grounded battery. Relay 34 becomes energized and closes'a circuit from ground, through its armature and front contact, a contact 41 and the power magnet of sequence "switch 19, to grounded battery, for driving this sequence switch out of position 14 into position 16. Lamp 32 is extinguished, indicating to the connecting operator that the C operator has taken care of the call.

When the subscriber at substation 110 tion 16.

restoreshis receiverto the switch-hoolgrelay 167 becomes de'energized, and opens the circuit of relay 143,,whereupon the above traced circuit, including relays 145 and 141, is established.

-Upon the energizationofrelay 145, relay 34 becomes 'denergiz'ed and closes a circuit from ground, through'its armature and back contact, a sequence switch contact 41, and

the lamp 33, :to grounded battery, indicating to: the connectingoperator thatdisconnectionwis desired.-If, at this time, the calling subscribers disconnect signal: (not shown) has also been actuated, the connecting oper ator removes plug 14 from jack 15, causing thus the denergization ofrelays 16 and 17. Relay 1'6:closes through sequence switch contact 42, a driving circuitfor sequence switch 19 and moves the same into position 1. The connecting operator also restores the sender, and the selectors 10 and 11.

,Assoon as sequence switch 19 is moved out of position 16, lamp 33 is extinguished and relay v130 becomes deenerg'izedi A circuit is closed thereupon from ground, through the armature andback contact of relay 130', a contact 170 and the power magnet of sequence switch 112 to grounded battery, for moving this 'sequenceswitch out of position 17 into position 1, in whichtposition, a circuit is closed from ground through the armature and front contactof relay 1 38, a sequence switch contact 137 and a lamp 17 2 togrounded battery.

Seeing the lighting of'lamp 172, the B op-' erator removes plug 137 from ack 136, causing thus the de't-inergization of relays 145 Relay 141 upon deenergization,

'and the relay combination 141, 143 and 145,

a simple-and eflicient means is provided for preventing the giving of a false disconnecting signal to the connecting operator in a system in which dry trunks interconnect two offices. In the absence of such delaying means, the supervisory relay 34 would be energized as soon as selector .11 seizes the trunk leading to plug 137, and would cause the moving of sequence switch 19 into posi- Relay 34.would then be deenergized upon the first energization of relay 145 and the connecting operator would thus receive a false disconnecting signal, and would sever the connection before the C operator had time to complete it by inserting plug 154 into jack 155.

While the invention has been, described as embodied in a semiautomatic telephone system, it will be apparent to those skilled in the art, that it is applicable to signaling systems of widely varying character, such as purely manual telephone systems, or systems in which not only the connecting, but also the B and C operators control selector switches for establishing connections.

WVhat is claimed is:

1. In a telephone exchangesystem, a plurality of lines, means for interconnecting two of said lines, a signal for indicating the stage of operation of said means, a disconnect signal, switching mechanism for successively operating said signals, and means for delaying the operation of said mechanism after the actuation of the first mentioned signal for a definite interval.

2. In a telephone exchange system, a plurality of lines, a plurality of ofiices, means for establishing a connection between two of said lines through said oflices, a signal operated upon the extension of said line from one ofiice to the other, a disconnect signal at one of said offices, means for actuating said disconnect signal after the operation of said first mentioned signal, and means at said other ofiice for delaying the actuation of said disconnect signal for a definite interval.

3. In a telephone exchange system, a plurality of lines, two ofiices, means for establishing a connection between two of said lines through said oflices, a dry trunk extending between said oflices, a supervisory relay at the first oiiice, and means associated with the second oflice for delaying the operation of said relay for a definite interval.

4. In a telephone exchange system, a plurality of lines, a plurality of oilices, means for establishing a connection between two of said lines through said ofiices, a trunk for interconnecting two of said oflices, means for supplying current to said trunk only during the establishment and the severing of connections, supervisory means controllable over said trunk, and means for preventing the operation of said supervisory means during the establishment of the connection.

5. In a telephone exchange system, a plurality of lines, three o liices, means for establishing a connection between two of said lines through said offices, a signal at the first oiiice, a relay at the second ofiice adapted to control said signal, a dry trunk interconnecting the second and third oliices, said relay being connected to the trunk, means at the third oifice for connecting battery to said trunk only during the establishment and severing of the connection, and means for rendering ineffective the operation of said relay during the establishment of the connection.

In witness whereof, I hereunto subscribe my name this 24th day of May, A. D. 1916.

ALBEN E. LUNDELL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

